A heat-ray-absorbing glass plate is required to have a low solar transmittance and a high visible light transmittance. That is, it is required to have a high ratio, Tv/Te, of the visible light transmittance (illuminant A, 2° visual field) (hereinafter also referred to as Tv) as defined in JIS R 3106 (1998) as a value calculated as 4 mm thickness of the glass plate to the solar transmittance (hereinafter also referred to as Te) as defined in JIS R 3106 (1998) as a value calculated as 4 mm thickness of the glass plate.
Moreover, it is sometimes required for a heat-ray-absorbing glass plate to have a low ultraviolet transmittance (hereinafter also referred to as Tuv) as defined in ISO 9050 (2003) simultaneously.
As heat-ray- and ultraviolet-absorbing glass plates, for example, the following glass plates have been proposed.
(1) A neutral gray colored glass composition containing:
a base glass portion consisting of:
SiO266 to 75 weight %,Na2O10 to 20,CaO 5 to 15,MgO 0 to 5,Al2O3 0 to 5, andK2O 0 to 5,and
a colorant portion essentially consisting of:
Fe2O3 (total iron)0.30 to 0.70 weight %,FeO0.21 weight % or less,CoO3 to 50 ppm,Se1 to 15 ppm,
in which the glass has a luminous transmittance of 60% or more at a thickness of 3.9 mm (Patent Document 1).
(2) An infrared and ultraviolet radiation absorbing blue colored glass composition containing:
a base glass portion consisting of:
SiO2about 66 to 75weight %,Na2Oabout 10 to 20weight %,CaOabout 5 to 15weight %,MgO0 to about 5weight %,Al2O30 to about 5weight %, andK2O0 to about 5weight %,and
a solar radiation absorbing portion and a colorant portion essentially consisting of:
total ironabout 0.40 to 1.0 weight %,CoOabout 4 to 40 ppm, andCr2O30 to about 100 ppm;
in which the glass has a redox of 0.35 to about 0.60; a luminous transmittance of at least 55%; a color characterized by a dominant wavelength of 485 to 489 nm and an excitation purity of about 3 to 18% (Patent Document 2).
(3) A glass plate containing, as represented by mass percentage based on components:
SiO2   65 to 75%,Al2O3  0.1 to 5%,MgO   1 to 6%,CaO   1 to 15%,Na2O + K2O   10 to 18%,total iron calculated as Fe2O3 0.10 to 0.42%,divalent iron calculated as FeO 0.05 to 0.25%,CoO0.0004 to 0.0050%, andSe0.0004 to 0.0018%,and
having a visible light transmittance being 70% or more at a thickness of 4 mm, a solar transmittance being 60%/c or less at a thickness of 4 mm, and a ultraviolet transmittance being 40% or less at a thickness of 4 mm (Patent Document 3).
(4) A neutral gray colored glass composition for obtaining automotive vision panels with reduced transmitted color shift characteristics, having
a base portion containing:
SiO265 to 75 weight %,Na2O10 to 20 weight %,CaO 5 to 15 weight %,MgO 0 to 5 weight %,Al2O3 0 to 5 weight %, andK2O 0 to 5 weight %,and
a major colorant containing:
Fe2O3 (total iron)0.30 to 0.75 weight %,CoO    0 to 15 ppm, andSe  1 to 15 ppm,
in which the glass has a luminous transmittance of at least 65% at a thickness of 3.9 mm; a redox ratio of from 0.26 to 0.675; a total solar energy transmittance (TSET) of 65% or less, and a standard transmitted color shift of less than 6 (Patent Document 4).
(5) A glass plate containing, as represented by mass percentage based on components:
SiO2   67 to 75%,Na2O   10 to 20%,CaO    5 to 15%,MgO    0 to 7%,Al2O3    0 to 7%,K2O    0 to 7%,total iron calculated as Fe2O3  0.25 to 0.70%,CeO2  0.01 to 1.0%,Se0.00001 to 0.05%,CoO 0.0001 to 0.05%, andTiO2    0 to 1.0%,and
having a mass ratio (FeO/t-Fe2O3) of divalent iron calculated as FeO to total iron calculated as Fe2O3 being 0.30 or more, a visible light transmittance being 65% or more, an infrared transmittance being 35% or less, an ultraviolet transmittance being 40% or less, and a total solar energy transmittance being 52% or less (Patent Document 5).